TABLE 1.

Key baking traits and involved genes.

Process name	Key genes	Use in baking	Strain traits	Citations
Maltose utilization	MAL loci: MALR; MALT; MALS	Needed to utilize maltose, the primary sugar in bread.	Baking strains tend to have multiple copies of MAL loci and/or MAL genes.	Duval et al., 2010; Bigey et al., 2020
Glucose suppression	MIG1	Glucose suppression shuts down maltose utilization, delays the start of fermentation, and decreases overall gasing ability.	Deletion of MIG1 has conflicting results, with glucose repression decreasing in some and increasing in others.	Keleher et al., 1992; Treitel and Carlson, 1995; Olsson and Nielsen, 2000
Osmotic stress	HOG1; AQR1; STL1; GDP1	Increased internal glycerol concentration aids cell survival; external glycerol aids in dough elasticity and thus gas retention.	HOG pathway is upregulated during dough fermentation; evidence of selection on osmosensor genes in strains used in other fermentations, but has not been examined for baking strains.	Albertyn et al., 1994; Hohmann, 2009; Aslankoohi et al., 2013, 2015; Brewster and Gustin, 2014; Heitmann et al., 2018
Trehalose and proline accumulation	TPS1; TPS2; NTH1; ATH1; MPR1; MPR2	Trehalose and proline increase cell survival and thus fermentation ability after freezing stress, for dough storage, and drying stress, during dried yeast processing.	Strains with increased trehalose and proline synthesis/retention have higher survivability.	Bell et al., 1992, 1998; Kopp et al., 1993; Alizadeh and Klionsky, 1996; Lewis et al., 1997; Samuel et al., 2000
Aromatic compounds	Varied	Yeast produced metabolites can change bread’s aromatic profile.	Individual strains can have significantly different aromatic profiles, with baking strains having had off-flavors/aromas bred out through artificial selection.	Olsson and Nielsen, 2000; Birch et al., 2013a, b; Aslankoohi et al., 2016; Dzialo et al., 2017